The present invention relates to dental drills and, in particular, to dental trephine drills.
A conventional dental technique for installing a prosthesis involves the installation of an anchor within a bore in the jaw bone, and the subsequent attachment of the prosthesis to the anchor. The bore is drilled by a trephine drill with the intention that a center core will remain at the base of the bore. The front end of the anchor is hollow in order to receive the core in telescoping fashion. The hollow end of the anchor contains throughholes through which the bone tissue can grow to secure the anchor in place.
In some instances the anchor is of the type containing self-tapping screw threads which cut through the bone tissue as the anchor is screwed into the bore. In such instances it is unnecessary for the diameter of the bore to be drilled with precision. However, the act of screwing self-tapping threads through the bone tissue has been determined to impart considerable trauma to the bone tissue, impairing the ability of the bone tissue to regenerate itself.
Also, presently available dental trephine drills do not easily cut through jaw bone tissue; drilling operations conducted with such drills are tedious and time-consuming, adding to the discomfort of the patient.
As described in copending, commonly assigned U.S. patent application Ser. Nos. 896,524, now U.S. Pat. No. 4,744,755 and 896,101, now U.S. Pat. No. 4,744,754 filed together on Aug. 13, 1986, the present inventor has determined that it is unnecessary to utilize self-tapping threads in order to secure an anchor in place. Rather, by drilling a bore having a diameter large enough to accommodate the outer diameter of the anchor, the anchor can be pushed directly into the bore, thereby eliminating the trauma to the bone caused by the screwing-in of self-tapping threads. However, conventional dental trephine drills have not produced satisfactory bores to enable the anchors to be conveniently pushed in place. Rather, the outer wall of the bore contains burrs which resist entry of the anchor. To remove the burrs, it has been necessary to repeatedly reciprocate the drill within the bore. Such a practice is time-consuming, increases the discomfort of the patient and may result in the bore being made of larger diameter than is desired for optimal results. That is, as noted in the above-referenced copending patent applications, it is desirable to enable the outer surface of the anchor to contact the wall of the bore in order to promote the occurrence of blood clotting and the retention of blood clots in the vicinity of the entire wall of the bore so that the regeneration of the bone tissue is accelerated. The attainment of this goal can be impaired if the bore diameter is excessively enlarged as the result of repeated reciprocation of the drill when the bore is being drilled.
Another concern during the drilling of bores in bone tissue relates to the fact that the bone tissue can be damaged by high temperature build-ups occurring as the result of frictional contact with the drill. Such temperature-induced damage can adversely affect the ability of the bone tissue to regenerate itself and grow against the anchor. Conventional trephine drills include a central passage for conducting fluid such as a saline solution or sterile water to the drill head intended for cooling the bone tissue and the drill head as well as flushing cuttings from the bore. However, as the bone core enters the front opening of the drill head, the flow of fluid is obstructed, whereby the benefits which would be otherwise attributable to the fluid flow are minimized. Also, such blockage of fluid flow creates a fluid pressure build-up which resists the advancement of the drill head.